Most drive-health tools report dozens of attributes and a green tick. The green tick is close to meaningless — a drive can pass its overall SMART status while carrying the specific values that predict imminent failure.
SMART’s overall verdict only fails once a manufacturer threshold is crossed, which is often far too late. The individual attributes tell you much earlier, if you read the right ones.
Reallocated sector count (05) — sectors retired because they could not be read reliably. Any non-zero value deserves attention; a rising one means back up now. Current pending sector count (C5) — sectors the drive has found unreadable but not yet retired. This is the single most useful early warning there is, and it is frequently non-zero while the overall status still reads healthy. Uncorrectable sector count (C6) — reads that failed outright. Reported uncorrectable errors (BB) and spin retry count (0A) complete the set; a rising spin retry count points at the motor or bearings.
Everything else — temperature, power-on hours, load cycles — is context rather than prediction.
On Windows, CrystalDiskInfo shows every attribute with raw values and is free; the manufacturer tools (SeaTools, WD Dashboard) add vendor-specific interpretation. On macOS, System Information gives a bare status and smartmontools gives the detail. On Linux, smartctl -a /dev/sdX is the standard.
Read the raw values rather than the normalised ones. Normalised values are scaled against a manufacturer threshold and can still look healthy while the raw count climbs — which is exactly how a drive passes its overall check while quietly accumulating pending sectors.
A rhythmic click every few seconds is the heads failing to find servo data — power it off. A scraping or grinding noise is heads contacting the platter surface, and every additional second causes permanent damage. A repeated buzz with no spin-up is a seized motor or stiction. A high-pitched whine that was not there before usually means bearings.
None of these have a software solution and all of them get worse with use. A drive that sounds wrong should be disconnected and assessed, not tested.
If pending or reallocated sectors are rising, copy the important data off before doing anything else — not after running a full surface scan, which reads every sector on a drive that has just told you it is struggling. Replace the drive rather than trying to repair it; a drive that has started retiring sectors will continue to.
Where the drive has already failed, recovery is from £300 +VAT for a single drive after a free 48-hour diagnostic, and most jobs are no fix, no fee.
Read the individual SMART attributes rather than the overall status — use CrystalDiskInfo on Windows or smartctl on macOS and Linux. The five that matter are reallocated sectors, current pending sectors, uncorrectable sectors, reported uncorrectable errors and spin retry count.
Not necessarily. SMART’s overall verdict only fails once a manufacturer threshold is crossed, which is often very late. A drive can report healthy while carrying a rising pending-sector count, and slowness is frequently the drive retrying unreadable sectors many times before succeeding.
Sectors the drive has found unreadable but has not yet retired. It is the most useful early warning available, and it is commonly non-zero while the overall SMART status still says healthy. Any rising value means back up now.
Not before backing up, and never on a drive that is making noise. A surface scan reads every sector, which is hours of stress on a drive that has already indicated it is struggling — and on a mechanically failing drive it can cause the damage you were trying to avoid.
A single hard drive, laptop or desktop, is from £300 plus VAT, fixed in a written quote after a free 48-hour diagnostic. Most jobs are no fix, no fee; clean-air and donor-part work carries a 50% deposit with the balance due only on success.